Using CRLF as line marker according to http 1.1 definition

According to http 1.1 definition http://www.w3.org/Protocols/rfc2616/rfc2616-sec2.html we should using CRLF as end-of-line marker. In my case some of my proxies will return 407 if it's not ended with '\r\n'. And we can see it clearly in twisted's [http client](https://github.com/twisted/twisted/blob/trunk/twisted/web/http.py#L410) implementation.